The present invention, in some embodiments thereof, relates to non-GVHD inducing anti-third party cells comprising central memory T-lymphocyte phenotype and, more particularly, but not exclusively, to the generation of same and use of same in transplantation and in disease treatment.
Bone marrow (BM) transplantation offers a curative treatment for many patients with hematological malignancies and other hematological disorders. However, the BM graft contains donor T cells which respond to the host antigens (Ags) and cause multi-system graft-versus-host disease (GVHD). In the early 80's bone marrow transplant (BMT), without the deleterious effect of GVHD, was demonstrated in the haploidentical (three HLA loci mismatched) settings, in severe combined immunodeficiency (SCID) patients. The problem of GVHD, which is almost uniformly lethal in such settings, was completely prevented by T cell depletion.
However, in leukemia patients, the clinical outcome of T cell depleted BM was disappointing, as the benefit of GVHD prevention was offset by a markedly increased rate of graft rejection. The rejection was shown to be mediated by radiochemotherapy resistant host derived T cells [Reisner et al., Proc Natl Acad Sci USA. (1986) 83:4012-4015]. One way to overcome this problem is to perform BMT following supra-lethal conditioning and functional inactivation of host T cells using immunosuppressive drugs. Nevertheless, this strategy is hampered by opportunistic infections due to slow immune reconstitution and considerable toxicities of the immunosuppressants.
While in high risk leukemia patients such transplant-related mortality can be acceptable, it would be intolerable if applied to patients with a long life expectancy. Therefore, the use of reduced intensity conditioning, with less severe immune ablation, to enable engraftment of T-depleted BM (TDBM) graft, which is associated with reduced risk for GVHD, is warranted. The establishment of donor type chimerism under such reduced conditioning represents a most desirable goal in transplantation biology, as it is generally associated with durable tolerance towards cells or tissues from the original donor. Yet, the marked levels of host immune cells surviving the mild preparatory regimens, represents a difficult barrier for the engraftment of donor cells.
One approach to overcome rejection of allogeneic hematopoietic stem cells made use of large doses of BM cells. It was first demonstrated in rodent models that a “megadose” of TDBM transplant can overcome T cell mediated graft rejection [Lapidot et al., Blood (1989) 73:2025-2032; Bachar-Lustig et al., Nat. Med. (1995) 1:1268-1273; Uharek et al., Blood (1992) 79:1612-1621]. However, a significant increase in the BM inoculum has been difficult to achieve in humans. To overcome this problem granulocytes colony stimulating factor (G-CSF), which facilitates mobilization of hematopoietic stem cells (HSCs, CD34+ cells in humans) from the BM, has been used to increase the yield of HSCs collected from the blood and these HSCs were supplemented to the conventional TDBM [Aversa et al., N Engl J. Med. (1998) 339:1186-1193; Aversa et al., J Clin Oncol. (2005) 23:3447-3454; Reisner and Martelli, Immunol Today (1999) 20:343-347; Handgretinger et al., Bone Marrow Transplant. (2001) 27:777-783].
The CD34 “megadose” transplants raised interesting questions as to how these cells overcome the barrier presented by host cytotoxic T-lymphocyte precursors (CTL-p). This question was answered, in part, by the finding that cells within the CD34 fraction are endowed with potent veto activity [Gur et al., Blood (2005) 105:2585-2593; Gur et al., Blood (2002) 99:4174-4181; Rachamim et al., Transplantation (1998) 65:1386-1393]. Other cell types have also been shown to mediate veto activity including T lymphocytes (e.g. CD8+ CTLs), natural killer cells and dendritic cells. Direct comparison of the veto reactivity of various cell types revealed that CTLs comprise the strongest veto effect [Reich-Zeliger et al., J. Immunol. (2004) 173:6654-6659].
One approach developed to generate veto CTLs without GVH reactivity was described by Reisner and co-workers, in which CTLs were stimulated against 3rd-party stimulators in the absence of exogenous IL-2. This approach was based on the observation that only activated CTLp were capable of surviving the IL-2 deprivation in the primary culture. This method was shown in vitro and in vivo to deplete GVH reactivity from the anti-3rd party veto CTLs [PCT Publication No. WO 2001/049243, Bachar-Lustig et al., Blood. 2003; 102:1943-1950; Aviner et al., Hum Immunol. (2005) 66:644-652]. Introduction of these anti-3rd party veto CTLs into a recipient (along with a transplant) prevented graft rejection without inducing GVHD (PCT Publication No. WO 2001/049243).
Various approaches have been contemplated for graft transplantation without graft rejection and/or graft versus host disease, some are summarized infra.
PCT Publication No. WO 2007/023491 discloses the use of tolerogenic cells for reducing or preventing graft rejection of a non-syngeneic graft in a subject. The tolerogenic cells disclosed (e.g. CD4+CD25+ cells) may be derived from any donor who is non-syngeneic with both the subject and the graft (“third-party” tolerogenic cells). The graft (e.g. bone marrow) may be derived from any graft donor who is allogeneic or xenogeneic with the subject.
PCT Publication No. WO 2002/102971 discloses the use of cultured hematopoietic progenitor cells (HPC) comprising enhanced veto activity for inducing tolerance to a transplant transplanted from a donor to a recipient. The tolerogenic cells disclosed preferably express CD33 and are administered prior to, concomitantly with or following transplantation of the transplant (e.g. cell or organ transplant).
PCT Publication No. WO 2002/043651 discloses the use of a non-GVHD inducing population of immune effector cells for disease treatment. In order to arrive at the non-GVHD inducing population of immune effector cells, a first cell population (e.g. T-lymphocytes) are co-cultured with a second cell population being non-syngeneic with the subject and non-syngeneic with the first cell population (e.g. EBV-infected B-lymphocytes) under conditions which include IL-2 starvation followed by IL-2 supplementation. The resultant immune effector cells may be used to treat diseases such as malignant diseases, viral diseases and autoimmune diseases.
U.S. Pat. No. 6,759,035 discloses methods of inhibiting graft rejection and inducing T cell tolerance in a solid organ transplant recipient. The methods disclosed comprise removing peripheral blood mononuclear cells (PBMC) from a donor and recipient, culturing the donor and recipient cells together in the presence of a compound that induces T cell suppressor activity (e.g. TGF-β, IL-15 and IL-2), and administering the recipient suppressor T cells to the recipient along with the transplant to prevent the recipient's T cells from killing donor cells, thereby inducing tolerance and long term survival of the transplant.
U.S. Pat. No. 6,803,036 discloses methods for treating donor cells to ameliorate graft versus host disease in a recipient patient. The methods disclosed comprise removing PBMCs from a donor and treating the cells with a suppressive composition (e.g. IL-10, IL-2, IL-4, IL-15 and TGF-β) for a time sufficient to induce T cell tolerance. The cells are then introduced to a recipient patient. The treated cells may be added to donor stem cells prior to introduction into the patient.